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Behind the Numbers: The Unimportance of Assists?

Posted by KCarpenter on January 19th, 2011

Pittsburgh, as Syracuse most recently learned, is a contender to win the national championship because they do one thing incredibly well and a lot of other things at a pretty high level. The one excellent thing they do is crash the offensive boards. They lead the nation in offensive rebounding rate, which is the driving force behind their current position as the most efficient offense in the country. The Panthers do a lot of other things well– shooting, defensive rebounding, controlling turnovers– but nothing they do, in terms of advanced stats, really jumped out at me until I noticed that they are second in the nation in assists to field goals made. 69.8% of Pittsburgh’s field goals are assisted. This is interesting and pretty cool, but I began to wonder if it even mattered.

Assists are really weird, because in a way that’s not true of any other individual stat, they don’t really measure individual performance at all. To get a credited assist, the passer’s teammate has to knock down shots. Surround a healthy Kyrie Irving with four clones of someone who shoots as well as I do, and as crisp, creative, and well-timed as his passes are, he is not going to get too many assists, solely because, well, I am a terrible shooter.The box score for this game will show he got no assists. Did Kyrie have a bad game? Were his passes worse than usual?

Jamie Dixon's Team Moves the Ball Well

No, probably not, and that’s a tricky question. From close to the beginning of basketball box scores, assists have been tracked. In fact, in the early days of individual statistics, assists were really about the only thing tracked besides points and rebounds. Why do we even track assists? Maybe just because we always have. On some level, it’s easy to see what assists are supposed to do: assists are supposed to be a measure of play-making through passing. But as I mentioned, assists really aren’t all that great at measuring true ball movement because the statistic is hopelessly tangled up with field goal percentage. A team that makes more shots should generally have more assists. We don’t keep track of who made a great pass that led to a missed shot, and that really throws off our view of skilled passing and playmaking, which, after all, assists are supposed to measure.

There are more problems than that. We largely assume that assists are almost always positive. Passing is good. The problem is that sometimes it isn’t. Let’s suppose that we are on the fast-break, and I have the ball and my man beat. It would be easy for me to hit an uncontested layup. Instead, I drop the ball back to you, and you hit a slightly more difficult uncontested mid-range shot. I decreased the chance of us scoring with that pass, but got credited with the assist. That was a bad assist and these happen all the time. If you don’t believe me, watch Rajon Rondo “gun” for assists the next time you watch the Boston Celtics play.

Assists really aren’t created equal. If I swing the ball to you and you launch a contested three, that’s not nearly as valuable as an assist where I lob it up to you for the dunk. The point-expectation is significantly lower on the first play than the second play. Tom Haberstroh has a great series of blog posts really delving into this concept as it pertains to the NBA. If you want to know which assists are the best assists and why, I’d recommend that you read his more detailedexplanations, but for now, I ask that you take my word on the (fairly uncontroversial) fact that some passes set up scoring better than others and some passes can actually hurt chances at scoring.

This brings us back to Pittsburgh and at least one crucial question. Is having a high assist-to-made field-goal ratio a good thing? While it may seem intuitively obvious that a lot of ball movement is crucial to success in basketball, let’s take a moment to consider some alternatives. There are lots of ways to score effectively without an assist: taking the ball strong to the hoop, utilizing a size advantage in the post, pull-up jumpers that put the defender on skates, and quick shots off the dribble after coming off a screen. I don’t know how many times I’ve heard that one of the most valuable assets in basketball is a player who can create their own shot. Wouldn’t a team with multiple, skilled players who each had an uncanny ability to create good shots for themselves have a lot of success and post a low assist-to-made-field-goal ratio? It certainly seems possible, at least in theory.

The two teams in Division I with the lowest assist-to-made-field-goal ratios are Alcorn State and Florida A&M, which are tied at a rate of 36.9%. Together, they have combined to beat one Division I opponent apiece. Yikes. The other teams that practice this low-assist style have similarly bad records, though there are a few interesting surprises on this end of the scale. Oklahoma State, Cleveland State and USC are all having respectable if not outstanding seasons without too much passing, but these teams are truly, at best, quartz crystals in the very rough.

By contrast, the top twenty teams in terms of assist-to-made-field-goal ratio includes not only Pittsburgh, but Notre Dame, Duquesne, Michigan State, Northwestern, Purdue, California, Minnesota and Louisville, which is certainly pretty good company. So, it seems that, despite all my speculation, getting a lot of assists seems to be an indicator of a good team. Well, sort of. The team that leads the country in assist-to-made-field-goal ratio is none other than Samford, a squad that assists on a remarkable 71.7% of all made field goals and which Ken Pomeroy estimates is the 269th best team in Division I. Yikes, again. So while teams that get lots of assists seem to be doing better on average than teams that get relatively few assists, don’t put too much stock in how well a team assists. Assists are just too squirrelly a statistic to draw much of a conclusion from it.

So, is Pittsburgh good? Of course they are. They are a good team because of their rebounding, their shooting, their defense, and their ball control. I also happen to think that they move the ball well and have players who create shots for each other. I just think that they could be 150th in assists-to-made-field-goals, play about the same way for Jamie Dixon, and still be this good. Assists mean something, but it really isn’t all that clear what.

3 Responses to “Behind the Numbers: The Unimportance of Assists?”

You left out an important aspect of assists: they’re pretty much the only subjective offensive stat. A pass that is an assist according to one official scorer may not be an assist according ot another. In one of Luke Winn’s recent Power Rankings, he charted Pittsburgh’s assists for one game, and came to the conclusion that assist totals in Pitt’s home games are inflated. This can also be seen by comparing their home Assist% (72.5) with their away Assist% (60.9), though this could actually be them playing differently on the road.

Absolutely true, just left it out because it is a whole other can of worms. Some really smart people have tracked the “house effect” on assists at different stadiums in the NBA, and I’m positive the same thing is true in college. Spoiler alert: John Stockton benefited from some generous Utah score-keepers. There’s also a pretty famous account of how one bored score-keeper basically give Nick van Exel a 20+ assist game.

I had no idea that was a concern. I’ve been charting defensive stats for a few college games (on my blog linked in name), and a couple times I’ve had mismatches between the number of turnovers or rebounds I record, and the number in the ESPN box score. I assumed I’d made a mistake, and credited/debited the “Team” line for the missing/extra event. Maybe I shouldn’t do that.